The present invention relates to a method for forming a single-portion package. The present invention also relates to a packaging machine. The present invention also relates to a blank web and a filled container.
The prior art in the food industry is to use food containers which have a closed form in horizontal cross-section, for the packing of liquid. foodstuffs. The said containers are formed by wrapping the blank to form a closed sidewall blank of horizontal cross-section and by closing both its open ends with an end member. One end member, the lid member, comprises a discharge hole which is opened to empty the contents of the container, and for this reason the said member is equipped with e.g. a closing flap, which when pulled off, reveals the hole. In connection with the production of the container, the container is filled aseptically with the contents through the open discharge hole, after which the discharge hole is sealed tightly. After this the container is ready for transportation and sale.
The stages described above are automated, and there are many known packaging machines that comprise a container-forming unit and a filling unit. In the container-forming unit the container closed with an end member as described above is formed, and in the filling unit the filling takes place through the discharge hole and the closing of the discharge hole is performed with a detachable closing element. For example European Patent 456011 shows and describes a container-forming unit of a packaging machine as described above. The end member, which may already have a closing flap adjacent to the filling hole, is inserted into the end of the sidewall blank and seamed onto it. After this, the end which has been left open is sealed at another unit with another end member, after which the container is filled through a filling hole in a filling unit and the closing flap is sealed Alternatively, the closing flap can be applied to the end of the container immediately prior to filling the container, and after the filling of the container the closing flap is sealed is such a way that it closes the hole tightly. The filling unit is described in European Patent 479010. International Publication WO 96/41743, on the other hand, presents the method for closing a liquid package filled with contents as described above. The liquid package is closed with a closing flap after the liquid has been introduced into the container through a filling hole in the end member, left open by a closing flap that is attached to the end member at its edge. International Publication WO 96/17772 presents a method in which a container formed by a sidewall blank and a bottom member is filled with contents through an open end, after which the lid member provided with a discharge hole closed with a closing flap is placed on the said end and seamed onto the laterally projecting flange on the upper surface of the end.
European Patent 501987 presents a lid which is either wholly detachable or partly detachable by means of perforation, the edges of which lid are folded downwards and seamed onto the inwards folded top edge of the container. After the lid has been attached, the container can be filled through the bottom, after which the bottom is sealed. The patent also mentions the possibility of filling the container through a filling hole made for the purpose, which is closed after filling by means of a closing flap.
The object of the present invention is to provide a new method for forming a container, which will give new possibilities for transferring the container from the container-forming unit to the filing unit and for filing, sterilizing and sealing the container to form a ready-made aseptically filled container. What is essential is that, after the sidewall blank has been formed from a blank by wrapping, it is closed with a lid member which has already been equipped with a detachable closing element that seals the discharge hole tightly, and the filing is performed through the bottom, which is left open, i.e. the container is in a way upside-down during the filing stage. After this the container is sealed tightly by seaming the bottom member to the sidewall blank.
By virtue of the present invention, the lid member can be produced so that it is equipped with a tightly closed closing element and the lid member can be seamed onto the sidewall blank already in the container-forming unit, and at the filling unit, in connection with the appropriate sterilisation and filling operations, the contents such as liquid foodstuffs will at the filling stage be fed in onto the lid member forming the bottom of the casing. The filling and operational stages preceding and following it are easier to perform through the large open end compared to the situation where the operational stages would have to be performed through a tight discharge hole. The packaging machine need comprise only two units, a container-forming unit where a container left open at one end is formed, and a filling unit where a container can be filled and sealed with another end member. It is unnecessary to have two successive container-forming units as presented in European Patent 456011.
In addition, it is possible to transfer the can which is formed in the container-forming unit on the forming mandrel and which comprises a sidewall blank and a bottom member, from the mandrel in the axial direction, for example pneumatically; along a suitable conveyor track, to the filling unit in such a way that it will enter the filling unit in an upright position with the lid member facing down.
Other preferred embodiments of the present invention will become apparent from the appended claims and the following detailed description.